With that being said Flowmaster had I believe a 60 series one time that were crazy quiet. I had them on a 540 for a short period and you would have never known about the powerplant they were so quiet. However they did stifle it on the Chassis dyno...
I definitely want to keep it free-flowing (the 451 is probably near 500 hp at the moment, and quite a bit more when I put the massaged aluminum heads on this winter that flow 293.5 cfm).
There is room for almost any muffler under the trunk...
Doesn't Flowmaster have a 70 series too?
